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/*
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 * Copyright (c) 2007-2012, Stephen Colebourne & Michael Nascimento Santos
 *
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
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package java.time;

import static java.time.temporal.ChronoField.DAY_OF_MONTH;
import static java.time.temporal.ChronoField.MONTH_OF_YEAR;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.time.chrono.Chronology;
import java.time.chrono.IsoChronology;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.format.DateTimeParseException;
import java.time.temporal.ChronoField;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalAdjuster;
import java.time.temporal.TemporalField;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalQuery;
import java.time.temporal.UnsupportedTemporalTypeException;
import java.time.temporal.ValueRange;
import java.util.Objects;

/**
 * A month-day in the ISO-8601 calendar system, such as {@code --12-03}.
 * <p>
 * {@code MonthDay} is an immutable date-time object that represents the combination
 * of a month and day-of-month. Any field that can be derived from a month and day,
 * such as quarter-of-year, can be obtained.
 * <p>
 * This class does not store or represent a year, time or time-zone.
 * For example, the value "December 3rd" can be stored in a {@code MonthDay}.
 * <p>
 * Since a {@code MonthDay} does not possess a year, the leap day of
 * February 29th is considered valid.
 * <p>
 * This class implements {@link TemporalAccessor} rather than {@link Temporal}.
 * This is because it is not possible to define whether February 29th is valid or not
 * without external information, preventing the implementation of plus/minus.
 * Related to this, {@code MonthDay} only provides access to query and set the fields
 * {@code MONTH_OF_YEAR} and {@code DAY_OF_MONTH}.
 * <p>
 * The ISO-8601 calendar system is the modern civil calendar system used today
 * in most of the world. It is equivalent to the proleptic Gregorian calendar
 * system, in which today's rules for leap years are applied for all time.
 * For most applications written today, the ISO-8601 rules are entirely suitable.
 * However, any application that makes use of historical dates, and requires them
 * to be accurate will find the ISO-8601 approach unsuitable.
 *
 * <p>
 * This is a <a href="{@docRoot}/java/lang/doc-files/ValueBased.html">value-based</a>
 * class; use of identity-sensitive operations (including reference equality
 * ({@code ==}), identity hash code, or synchronization) on instances of
 * {@code MonthDay} may have unpredictable results and should be avoided.
 * The {@code equals} method should be used for comparisons.
 *
 * @implSpec This class is immutable and thread-safe.
 * @since 1.8
 */
public final class MonthDay
    implements TemporalAccessor, TemporalAdjuster, Comparable<MonthDay>, Serializable {

  /**
   * Serialization version.
   */
  private static final long serialVersionUID = -939150713474957432L;
  /**
   * Parser.
   */
  private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
      .appendLiteral("--")
      .appendValue(MONTH_OF_YEAR, 2)
      .appendLiteral('-')
      .appendValue(DAY_OF_MONTH, 2)
      .toFormatter();

  /**
   * The month-of-year, not null.
   */
  private final int month;
  /**
   * The day-of-month.
   */
  private final int day;

  //-----------------------------------------------------------------------

  /**
   * Obtains the current month-day from the system clock in the default time-zone.
   * <p>
   * This will query the {@link Clock#systemDefaultZone() system clock} in the default
   * time-zone to obtain the current month-day.
   * <p>
   * Using this method will prevent the ability to use an alternate clock for testing
   * because the clock is hard-coded.
   *
   * @return the current month-day using the system clock and default time-zone, not null
   */
  public static MonthDay now() {
    return now(Clock.systemDefaultZone());
  }

  /**
   * Obtains the current month-day from the system clock in the specified time-zone.
   * <p>
   * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current month-day.
   * Specifying the time-zone avoids dependence on the default time-zone.
   * <p>
   * Using this method will prevent the ability to use an alternate clock for testing
   * because the clock is hard-coded.
   *
   * @param zone the zone ID to use, not null
   * @return the current month-day using the system clock, not null
   */
  public static MonthDay now(ZoneId zone) {
    return now(Clock.system(zone));
  }

  /**
   * Obtains the current month-day from the specified clock.
   * <p>
   * This will query the specified clock to obtain the current month-day.
   * Using this method allows the use of an alternate clock for testing.
   * The alternate clock may be introduced using {@link Clock dependency injection}.
   *
   * @param clock the clock to use, not null
   * @return the current month-day, not null
   */
  public static MonthDay now(Clock clock) {
    final LocalDate now = LocalDate.now(clock);  // called once
    return MonthDay.of(now.getMonth(), now.getDayOfMonth());
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an instance of {@code MonthDay}.
   * <p>
   * The day-of-month must be valid for the month within a leap year.
   * Hence, for February, day 29 is valid.
   * <p>
   * For example, passing in April and day 31 will throw an exception, as
   * there can never be April 31st in any year. By contrast, passing in
   * February 29th is permitted, as that month-day can sometimes be valid.
   *
   * @param month the month-of-year to represent, not null
   * @param dayOfMonth the day-of-month to represent, from 1 to 31
   * @return the month-day, not null
   * @throws DateTimeException if the value of any field is out of range, or if the day-of-month is
   * invalid for the month
   */
  public static MonthDay of(Month month, int dayOfMonth) {
    Objects.requireNonNull(month, "month");
    DAY_OF_MONTH.checkValidValue(dayOfMonth);
    if (dayOfMonth > month.maxLength()) {
      throw new DateTimeException("Illegal value for DayOfMonth field, value " + dayOfMonth +
          " is not valid for month " + month.name());
    }
    return new MonthDay(month.getValue(), dayOfMonth);
  }

  /**
   * Obtains an instance of {@code MonthDay}.
   * <p>
   * The day-of-month must be valid for the month within a leap year.
   * Hence, for month 2 (February), day 29 is valid.
   * <p>
   * For example, passing in month 4 (April) and day 31 will throw an exception, as
   * there can never be April 31st in any year. By contrast, passing in
   * February 29th is permitted, as that month-day can sometimes be valid.
   *
   * @param month the month-of-year to represent, from 1 (January) to 12 (December)
   * @param dayOfMonth the day-of-month to represent, from 1 to 31
   * @return the month-day, not null
   * @throws DateTimeException if the value of any field is out of range, or if the day-of-month is
   * invalid for the month
   */
  public static MonthDay of(int month, int dayOfMonth) {
    return of(Month.of(month), dayOfMonth);
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an instance of {@code MonthDay} from a temporal object.
   * <p>
   * This obtains a month-day based on the specified temporal.
   * A {@code TemporalAccessor} represents an arbitrary set of date and time information,
   * which this factory converts to an instance of {@code MonthDay}.
   * <p>
   * The conversion extracts the {@link ChronoField#MONTH_OF_YEAR MONTH_OF_YEAR} and
   * {@link ChronoField#DAY_OF_MONTH DAY_OF_MONTH} fields.
   * The extraction is only permitted if the temporal object has an ISO
   * chronology, or can be converted to a {@code LocalDate}.
   * <p>
   * This method matches the signature of the functional interface {@link TemporalQuery}
   * allowing it to be used as a query via method reference, {@code MonthDay::from}.
   *
   * @param temporal the temporal object to convert, not null
   * @return the month-day, not null
   * @throws DateTimeException if unable to convert to a {@code MonthDay}
   */
  public static MonthDay from(TemporalAccessor temporal) {
    if (temporal instanceof MonthDay) {
      return (MonthDay) temporal;
    }
    try {
      if (IsoChronology.INSTANCE.equals(Chronology.from(temporal)) == false) {
        temporal = LocalDate.from(temporal);
      }
      return of(temporal.get(MONTH_OF_YEAR), temporal.get(DAY_OF_MONTH));
    } catch (DateTimeException ex) {
      throw new DateTimeException("Unable to obtain MonthDay from TemporalAccessor: " +
          temporal + " of type " + temporal.getClass().getName(), ex);
    }
  }

  //-----------------------------------------------------------------------

  /**
   * Obtains an instance of {@code MonthDay} from a text string such as {@code --12-03}.
   * <p>
   * The string must represent a valid month-day.
   * The format is {@code --MM-dd}.
   *
   * @param text the text to parse such as "--12-03", not null
   * @return the parsed month-day, not null
   * @throws DateTimeParseException if the text cannot be parsed
   */
  public static MonthDay parse(CharSequence text) {
    return parse(text, PARSER);
  }

  /**
   * Obtains an instance of {@code MonthDay} from a text string using a specific formatter.
   * <p>
   * The text is parsed using the formatter, returning a month-day.
   *
   * @param text the text to parse, not null
   * @param formatter the formatter to use, not null
   * @return the parsed month-day, not null
   * @throws DateTimeParseException if the text cannot be parsed
   */
  public static MonthDay parse(CharSequence text, DateTimeFormatter formatter) {
    Objects.requireNonNull(formatter, "formatter");
    return formatter.parse(text, MonthDay::from);
  }

  //-----------------------------------------------------------------------

  /**
   * Constructor, previously validated.
   *
   * @param month the month-of-year to represent, validated from 1 to 12
   * @param dayOfMonth the day-of-month to represent, validated from 1 to 29-31
   */
  private MonthDay(int month, int dayOfMonth) {
    this.month = month;
    this.day = dayOfMonth;
  }

  //-----------------------------------------------------------------------

  /**
   * Checks if the specified field is supported.
   * <p>
   * This checks if this month-day can be queried for the specified field.
   * If false, then calling the {@link #range(TemporalField) range} and
   * {@link #get(TemporalField) get} methods will throw an exception.
   * <p>
   * If the field is a {@link ChronoField} then the query is implemented here.
   * The supported fields are:
   * <ul>
   * <li>{@code MONTH_OF_YEAR}
   * <li>{@code YEAR}
   * </ul>
   * All other {@code ChronoField} instances will return false.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.isSupportedBy(TemporalAccessor)}
   * passing {@code this} as the argument.
   * Whether the field is supported is determined by the field.
   *
   * @param field the field to check, null returns false
   * @return true if the field is supported on this month-day, false if not
   */
  @Override
  public boolean isSupported(TemporalField field) {
    if (field instanceof ChronoField) {
      return field == MONTH_OF_YEAR || field == DAY_OF_MONTH;
    }
    return field != null && field.isSupportedBy(this);
  }

  /**
   * Gets the range of valid values for the specified field.
   * <p>
   * The range object expresses the minimum and maximum valid values for a field.
   * This month-day is used to enhance the accuracy of the returned range.
   * If it is not possible to return the range, because the field is not supported
   * or for some other reason, an exception is thrown.
   * <p>
   * If the field is a {@link ChronoField} then the query is implemented here.
   * The {@link #isSupported(TemporalField) supported fields} will return
   * appropriate range instances.
   * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.rangeRefinedBy(TemporalAccessor)}
   * passing {@code this} as the argument.
   * Whether the range can be obtained is determined by the field.
   *
   * @param field the field to query the range for, not null
   * @return the range of valid values for the field, not null
   * @throws DateTimeException if the range for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported
   */
  @Override
  public ValueRange range(TemporalField field) {
    if (field == MONTH_OF_YEAR) {
      return field.range();
    } else if (field == DAY_OF_MONTH) {
      return ValueRange.of(1, getMonth().minLength(), getMonth().maxLength());
    }
    return TemporalAccessor.super.range(field);
  }

  /**
   * Gets the value of the specified field from this month-day as an {@code int}.
   * <p>
   * This queries this month-day for the value of the specified field.
   * The returned value will always be within the valid range of values for the field.
   * If it is not possible to return the value, because the field is not supported
   * or for some other reason, an exception is thrown.
   * <p>
   * If the field is a {@link ChronoField} then the query is implemented here.
   * The {@link #isSupported(TemporalField) supported fields} will return valid
   * values based on this month-day.
   * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
   * passing {@code this} as the argument. Whether the value can be obtained,
   * and what the value represents, is determined by the field.
   *
   * @param field the field to get, not null
   * @return the value for the field
   * @throws DateTimeException if a value for the field cannot be obtained or the value is outside
   * the range of valid values for the field
   * @throws UnsupportedTemporalTypeException if the field is not supported or the range of values
   * exceeds an {@code int}
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override  // override for Javadoc
  public int get(TemporalField field) {
    return range(field).checkValidIntValue(getLong(field), field);
  }

  /**
   * Gets the value of the specified field from this month-day as a {@code long}.
   * <p>
   * This queries this month-day for the value of the specified field.
   * If it is not possible to return the value, because the field is not supported
   * or for some other reason, an exception is thrown.
   * <p>
   * If the field is a {@link ChronoField} then the query is implemented here.
   * The {@link #isSupported(TemporalField) supported fields} will return valid
   * values based on this month-day.
   * All other {@code ChronoField} instances will throw an {@code UnsupportedTemporalTypeException}.
   * <p>
   * If the field is not a {@code ChronoField}, then the result of this method
   * is obtained by invoking {@code TemporalField.getFrom(TemporalAccessor)}
   * passing {@code this} as the argument. Whether the value can be obtained,
   * and what the value represents, is determined by the field.
   *
   * @param field the field to get, not null
   * @return the value for the field
   * @throws DateTimeException if a value for the field cannot be obtained
   * @throws UnsupportedTemporalTypeException if the field is not supported
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override
  public long getLong(TemporalField field) {
    if (field instanceof ChronoField) {
      switch ((ChronoField) field) {
        // alignedDOW and alignedWOM not supported because they cannot be set in with()
        case DAY_OF_MONTH:
          return day;
        case MONTH_OF_YEAR:
          return month;
      }
      throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
    }
    return field.getFrom(this);
  }

  //-----------------------------------------------------------------------

  /**
   * Gets the month-of-year field from 1 to 12.
   * <p>
   * This method returns the month as an {@code int} from 1 to 12.
   * Application code is frequently clearer if the enum {@link Month}
   * is used by calling {@link #getMonth()}.
   *
   * @return the month-of-year, from 1 to 12
   * @see #getMonth()
   */
  public int getMonthValue() {
    return month;
  }

  /**
   * Gets the month-of-year field using the {@code Month} enum.
   * <p>
   * This method returns the enum {@link Month} for the month.
   * This avoids confusion as to what {@code int} values mean.
   * If you need access to the primitive {@code int} value then the enum
   * provides the {@link Month#getValue() int value}.
   *
   * @return the month-of-year, not null
   * @see #getMonthValue()
   */
  public Month getMonth() {
    return Month.of(month);
  }

  /**
   * Gets the day-of-month field.
   * <p>
   * This method returns the primitive {@code int} value for the day-of-month.
   *
   * @return the day-of-month, from 1 to 31
   */
  public int getDayOfMonth() {
    return day;
  }

  //-----------------------------------------------------------------------

  /**
   * Checks if the year is valid for this month-day.
   * <p>
   * This method checks whether this month and day and the input year form
   * a valid date. This can only return false for February 29th.
   *
   * @param year the year to validate
   * @return true if the year is valid for this month-day
   * @see Year#isValidMonthDay(MonthDay)
   */
  public boolean isValidYear(int year) {
    return (day == 29 && month == 2 && Year.isLeap(year) == false) == false;
  }

  //-----------------------------------------------------------------------

  /**
   * Returns a copy of this {@code MonthDay} with the month-of-year altered.
   * <p>
   * This returns a month-day with the specified month.
   * If the day-of-month is invalid for the specified month, the day will
   * be adjusted to the last valid day-of-month.
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param month the month-of-year to set in the returned month-day, from 1 (January) to 12
   * (December)
   * @return a {@code MonthDay} based on this month-day with the requested month, not null
   * @throws DateTimeException if the month-of-year value is invalid
   */
  public MonthDay withMonth(int month) {
    return with(Month.of(month));
  }

  /**
   * Returns a copy of this {@code MonthDay} with the month-of-year altered.
   * <p>
   * This returns a month-day with the specified month.
   * If the day-of-month is invalid for the specified month, the day will
   * be adjusted to the last valid day-of-month.
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param month the month-of-year to set in the returned month-day, not null
   * @return a {@code MonthDay} based on this month-day with the requested month, not null
   */
  public MonthDay with(Month month) {
    Objects.requireNonNull(month, "month");
    if (month.getValue() == this.month) {
      return this;
    }
    int day = Math.min(this.day, month.maxLength());
    return new MonthDay(month.getValue(), day);
  }

  /**
   * Returns a copy of this {@code MonthDay} with the day-of-month altered.
   * <p>
   * This returns a month-day with the specified day-of-month.
   * If the day-of-month is invalid for the month, an exception is thrown.
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param dayOfMonth the day-of-month to set in the return month-day, from 1 to 31
   * @return a {@code MonthDay} based on this month-day with the requested day, not null
   * @throws DateTimeException if the day-of-month value is invalid, or if the day-of-month is
   * invalid for the month
   */
  public MonthDay withDayOfMonth(int dayOfMonth) {
    if (dayOfMonth == this.day) {
      return this;
    }
    return of(month, dayOfMonth);
  }

  //-----------------------------------------------------------------------

  /**
   * Queries this month-day using the specified query.
   * <p>
   * This queries this month-day using the specified query strategy object.
   * The {@code TemporalQuery} object defines the logic to be used to
   * obtain the result. Read the documentation of the query to understand
   * what the result of this method will be.
   * <p>
   * The result of this method is obtained by invoking the
   * {@link TemporalQuery#queryFrom(TemporalAccessor)} method on the
   * specified query passing {@code this} as the argument.
   *
   * @param <R> the type of the result
   * @param query the query to invoke, not null
   * @return the query result, null may be returned (defined by the query)
   * @throws DateTimeException if unable to query (defined by the query)
   * @throws ArithmeticException if numeric overflow occurs (defined by the query)
   */
  @SuppressWarnings("unchecked")
  @Override
  public <R> R query(TemporalQuery<R> query) {
    if (query == TemporalQueries.chronology()) {
      return (R) IsoChronology.INSTANCE;
    }
    return TemporalAccessor.super.query(query);
  }

  /**
   * Adjusts the specified temporal object to have this month-day.
   * <p>
   * This returns a temporal object of the same observable type as the input
   * with the month and day-of-month changed to be the same as this.
   * <p>
   * The adjustment is equivalent to using {@link Temporal#with(TemporalField, long)}
   * twice, passing {@link ChronoField#MONTH_OF_YEAR} and
   * {@link ChronoField#DAY_OF_MONTH} as the fields.
   * If the specified temporal object does not use the ISO calendar system then
   * a {@code DateTimeException} is thrown.
   * <p>
   * In most cases, it is clearer to reverse the calling pattern by using
   * {@link Temporal#with(TemporalAdjuster)}:
   * <pre>
   *   // these two lines are equivalent, but the second approach is recommended
   *   temporal = thisMonthDay.adjustInto(temporal);
   *   temporal = temporal.with(thisMonthDay);
   * </pre>
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param temporal the target object to be adjusted, not null
   * @return the adjusted object, not null
   * @throws DateTimeException if unable to make the adjustment
   * @throws ArithmeticException if numeric overflow occurs
   */
  @Override
  public Temporal adjustInto(Temporal temporal) {
    if (Chronology.from(temporal).equals(IsoChronology.INSTANCE) == false) {
      throw new DateTimeException("Adjustment only supported on ISO date-time");
    }
    temporal = temporal.with(MONTH_OF_YEAR, month);
    return temporal.with(DAY_OF_MONTH, Math.min(temporal.range(DAY_OF_MONTH).getMaximum(), day));
  }

  /**
   * Formats this month-day using the specified formatter.
   * <p>
   * This month-day will be passed to the formatter to produce a string.
   *
   * @param formatter the formatter to use, not null
   * @return the formatted month-day string, not null
   * @throws DateTimeException if an error occurs during printing
   */
  public String format(DateTimeFormatter formatter) {
    Objects.requireNonNull(formatter, "formatter");
    return formatter.format(this);
  }

  //-----------------------------------------------------------------------

  /**
   * Combines this month-day with a year to create a {@code LocalDate}.
   * <p>
   * This returns a {@code LocalDate} formed from this month-day and the specified year.
   * <p>
   * A month-day of February 29th will be adjusted to February 28th in the resulting
   * date if the year is not a leap year.
   * <p>
   * This instance is immutable and unaffected by this method call.
   *
   * @param year the year to use, from MIN_YEAR to MAX_YEAR
   * @return the local date formed from this month-day and the specified year, not null
   * @throws DateTimeException if the year is outside the valid range of years
   */
  public LocalDate atYear(int year) {
    return LocalDate.of(year, month, isValidYear(year) ? day : 28);
  }

  //-----------------------------------------------------------------------

  /**
   * Compares this month-day to another month-day.
   * <p>
   * The comparison is based first on value of the month, then on the value of the day.
   * It is "consistent with equals", as defined by {@link Comparable}.
   *
   * @param other the other month-day to compare to, not null
   * @return the comparator value, negative if less, positive if greater
   */
  @Override
  public int compareTo(MonthDay other) {
    int cmp = (month - other.month);
    if (cmp == 0) {
      cmp = (day - other.day);
    }
    return cmp;
  }

  /**
   * Checks if this month-day is after the specified month-day.
   *
   * @param other the other month-day to compare to, not null
   * @return true if this is after the specified month-day
   */
  public boolean isAfter(MonthDay other) {
    return compareTo(other) > 0;
  }

  /**
   * Checks if this month-day is before the specified month-day.
   *
   * @param other the other month-day to compare to, not null
   * @return true if this point is before the specified month-day
   */
  public boolean isBefore(MonthDay other) {
    return compareTo(other) < 0;
  }

  //-----------------------------------------------------------------------

  /**
   * Checks if this month-day is equal to another month-day.
   * <p>
   * The comparison is based on the time-line position of the month-day within a year.
   *
   * @param obj the object to check, null returns false
   * @return true if this is equal to the other month-day
   */
  @Override
  public boolean equals(Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj instanceof MonthDay) {
      MonthDay other = (MonthDay) obj;
      return month == other.month && day == other.day;
    }
    return false;
  }

  /**
   * A hash code for this month-day.
   *
   * @return a suitable hash code
   */
  @Override
  public int hashCode() {
    return (month << 6) + day;
  }

  //-----------------------------------------------------------------------

  /**
   * Outputs this month-day as a {@code String}, such as {@code --12-03}.
   * <p>
   * The output will be in the format {@code --MM-dd}:
   *
   * @return a string representation of this month-day, not null
   */
  @Override
  public String toString() {
    return new StringBuilder(10).append("--")
        .append(month < 10 ? "0" : "").append(month)
        .append(day < 10 ? "-0" : "-").append(day)
        .toString();
  }

  //-----------------------------------------------------------------------

  /**
   * Writes the object using a
   * <a href="../../serialized-form.html#java.time.Ser">dedicated serialized form</a>.
   *
   * @return the instance of {@code Ser}, not null
   * @serialData <pre>
   *  out.writeByte(13);  // identifies a MonthDay
   *  out.writeByte(month);
   *  out.writeByte(day);
   * </pre>
   */
  private Object writeReplace() {
    return new Ser(Ser.MONTH_DAY_TYPE, this);
  }

  /**
   * Defend against malicious streams.
   *
   * @param s the stream to read
   * @throws InvalidObjectException always
   */
  private void readObject(ObjectInputStream s) throws InvalidObjectException {
    throw new InvalidObjectException("Deserialization via serialization delegate");
  }

  void writeExternal(DataOutput out) throws IOException {
    out.writeByte(month);
    out.writeByte(day);
  }

  static MonthDay readExternal(DataInput in) throws IOException {
    byte month = in.readByte();
    byte day = in.readByte();
    return MonthDay.of(month, day);
  }

}
